Panasonic ZEQUO 6400, Operating Instructions Manual

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74. Spanning Tree Protocol (STP) commands
859
74.Spanning Tree Protocol (STP)
commands

STP
STP (Spanning Tree Protocol) is a function to provide path redundancy while
preventing loops in a network established by connecting multiple bridges. Even if one
end of a communication route is down, the function can continue communications by
detouring the route.
In general, if a cable is connected in a loop form, a phenomenon called broadcast
storm, where frames keep looping permanently, occurs and causes the network to go
down.
The SPT function interchanges control frames called BPDU frames between Switching
Hubs to calculate the shortest route. Automatic port blocking to prevent frames from
looping allows you to establish a network which logically never has loops.
If a failure occurs on a route, the communication route can be recovered within 50
seconds or less.
Figure 74-1 STP overview
 RSTP
RSTP (Rapid Spanning Tree Protocol) is a modified STP protocol to reduce recovery
time to several seconds during a route failure.
When changing a route, the RSTP function determines port roles and changes the
route immediately through information exchanges (proposal/agreement) between
Switching Hubs instead of timers used in STP.